Tensioning means for flat knitting machines



Feb. 16, 1960 P. J. SCHOENSTER TENSIONING MEANS FOR FLAT KNITTING MACHINES Filed Jan. 16, 1956 FIG.2

INVENTOR.

PETER J. SCHOENSTER ATTORNEY a 2,924,957 I TENSIONING MEANS FOR FLAT KNITTINGMACHINES Ieter J.?-Scl10enster, Teaneck, N.J., assignor to Alfred Hofman n& Co., West New York, N.J., a corporation of New. Jersey a Application 'January 16, 1956, Serial Na. 559,418

Claims. on. 66-86) This invention relates to improved'means for tensioning the yarn' sheet of a flat knitting machine, as such sheet moves ,in a path between the yarn supply beam and the knitting elements of'the machine. i

.In conventional arrangements for tensioning the yarn sheet, it is common to use an oscillatory bar which extends the length of the machine and has arms extending therefromwfor mounting a tension rod over which the yarn sheet passes, together with spring loading means abutting levers extending from the 'bar. In this manner, tension is provided to keep the yarn sheet taut during the knitting cycle.. However, the spring loading means,

which usually takes' the form of an elongated compression spring, is operative to provide for a wide range of up and down movements of the tension rod.

Furthermore, such conventional yarn tensioning arrangements are also used to actuate braking mechanisms which control the rotation of the yarn supply beam, and hence, the flow of yarn from the beam, as typically sho'wn in Patent 2,395,807,- 2,521,218, e tc., assigned to the aswhich are detrimental'to the accurate control of the ten-' sion of-"the yarn-sheet. The advent of modern, high speed knitting machines, particularly-the tricot type, "made it desirable to improve the controlof the movement of theyarn' sheet from the yarn supply beam. Such irriprovedcontrol means may take" the form of a positive drive for" the beam and" control means for the drive, as shown in Patent 2,707,380 assigned to the assignee ofthe instant application.

While attempts have been-made to effect improvements in the yarntensioning means, as by connecting the tensio'n'rod to the bar by flat 'springs and fixing the bar against'o scillatory movement, such arrangements which still havea wide range of fluctuations in the up and down movement of the tension rod, result in snarling of the yarns, 'asrwell as faults in the-knitted'fabric such as shade marks, pin holes and the like. Accordingly, an object of this invention is to provide improved means for tensioning the yarn sheet in a fiat knitting machine, which includes in addition to the usual spring means allowing a wide range of fluctuations in the movement of the tension rod, auxiliary means for limit ing the overall pperatingrange of the tension rod in accordance with precisionltension requirements of the yarn as-dictated by the composite, related motion of the needles, sinkers and yarn guides of the machine, in relation to the yarn supply.

,QAhQthero 1e; fofjthisinvelntionis toprovide improved Un ted Stew Pa in machines having positive yarn feeding means operative to supply aconstant length of yarn predetermined by the quality of the fabric being knitted, such tensioning means being operative to provide suitable tension commensurate with changes in the yarn length temporarily occasioned by the motions of the knitting elements of the machine.

A further object of this invention is to provide improved yarn tensioning means of the character described wherein sheet between the yarn supply beam and the knitting elements of a flat knitting machine;

Fig.- 2 is a diagrammatic showing of'yarn tensioning means "embodying the invention; and

Fig. 3 is a diagrammatic showing of a modified form of the invention.

Referringin detail to the drawing and particularly to Fig.1, 1'0 designates conventional means, well known in the art, for tensioning the yarn sheet in a fiat knitting machine' The same comprises an elongated bar 11 mounted in suitable bearings along the length of the knitting machine, for oscillatory movement. 12 extends parallel to bar 11 and is rigidly attached thereto by spaced arms 13. Levers 14 extend from bar 11 in a direction opposite to that of arms 13, with elongated compression springs 15 extending at right angles to said levers and abutting the same. Springs 15 are mounted on rods 16 which are attached at their lower ends to the machine frame, as at 17. The free ends of rods 16 are threaded as at 18 to receive nuts 19 for adjusting the compression of springs 15 as the same abuts levers 14,

As the yarns Y move from the yarn supply beam 20 toward the knitting elements indicated at 21, they pass over the tension rod 12; the springs 15 being operative to keep the yarns Y taut during the knitting cycle. It willbe apparent that the rod 12 has a wide range of up and down movement within the compression limits of springs ISL The movement of the tension rod 12 may also be used to actuate brake mechanism, not shown, for controlling the rotation of the beam 20 and thus, the flow of yarns Y.

With" the advent'of high speed knitting machines operating at 1,000 c.p.'m. or more, and with the use of mechanisms' for-"positively driving the yarn beams to supply a predetermined linear length of yarn to the knitting elements, .in timed relation to the knitting speed of the matheir respective motions, require a temporary following i of yarn, in addition to the length of yarn supplied for the'specificloop construction.

H 1 Such additional following of 'yarn supplied to the},

tensioning'means of the character described, foruse knitting elements in the course'of the'knitting cycle, is

A tension rodprovided by the operation of the tension rod as the same yields in response to compression of the springs described above. However, it is noted that the temporary requirement for yielding additional yarn, is rather limited in comparison to the degree of yield of the tension rod as afforded by the conventional, spring arrangements 7 of up and down movements of the tension rod during knitting operations. To this end there is provided auxiliaryresilient means inthe form of rubber or spring elements having high, frequency reactiveness which. is quickly responsive to the yarn requirements during the knitting cycles of high speed knitting machines.

Thus, as shown in Fig. 2, the improved yarn tensioning means 10a embodying the invention, comprises the oscillatory bar 11 with tension rod 12 fixed thereto by spaced arms 13 extending transversely thereof, a single arm 13 being shown. A lever 14 extends transversely from'bar 11 away from arm 13. A tension spring 15a is anchored-at one end to the machine frame at 17aand is connected at the other end to lever 14, thus supplying tension for the yarns Y moving from yarn supply beam 20a over tension rod 12 to the knitting elements, as previously described.

Preferably, yarn supply beam 20a is positively driven by a gear arrangement 22 operated by suitable speed control means generally indicated at 23. Such positive drive may take the forrn of variable speed mechanisms interposed between the main camshaft of the :knitting machine, not shown, and the gear arrangement 22 and responsive to changes in the diameter of the beam 20a,

all as detailed in Patent 2,707,380; and being operative to provide a constant linear feed of yarn to the knitting elements of the machine.

Primarily, spring 15a is effective to prevent an undue loosening of the yarns in yarn sheet Y in its movement to the knitting elements, as may be occasioned by an excessive supply of yarn for the specific fabric construction to be knitted,,or as a safety means for taking up excessive yarn inthe event of an accidental overdrive required for the formation courses of the knitted fabric.

of the successive loops and It is understood that in the arrangement shown in Fig. 2, a short compression spring or other resilient memher having the proper highfrequency reactiveness, may replace rubber cushion 24. Also, an elongated compression. spring may be used in lieu of tension spring 15a, as suggested ,in Fig. 1. I Y

The instantinven't-ion ma-y also be embodied in the form shown in Fig.3, wherein the cushion 24a is mounted on the downwardly extending arm 28 of a right angle bracket .29 attached to a portion '30 of the'machine frame. Oscillatory. bar 11, with associated tension "rod 12,. arms 13 and levers 14, islocated so that levers 14 are disposed in opposed relation to cushions 24a and abut the same as tension rod 12 moves downwardly against the action of tension spring 1511 interconnecting the outer end of lever 14 and frame portion 30. I

Preferably, cushion 2411, may be mounted in'adjusted positions along bracket arm 28, by means of a threaded member '31- extendingrfrom said :cushionand receivable in openings 32 formed .along said bracket arm and re tainediin place by nut .33...-With the position ofgcushion 24a .as .indicatedin :solid lines, the leverage action between arms .13 and levers is in theratio of about 1:1, whereby .if:cushion 24a is compressed axially to the extent of about /s"'., tension rod 12'will "yield-under a given (tension :load of tthernoving yarns ofabout A3".

However, if cushiony2-4z1-v is moved ,to .a lower positionion bracket arm 28, as indicated'in dotted lines, abut ment:o'f:lever.14 will occur :at a point equal to .about /3 of the length of said lever. Thus, with-a compression of cushion 24a=ofthe order of Ms", there will ,be pro- 1 vided ta leverage rangeinthe motion :of tension rod 12 amounting to about: /3".

,It is thus possible to changewthe operating range of the yarn *tensioning .means jasymay be required by the knitting details, ofdiiferent types offabrics-and yarns, yet

i providing suitable, auxiliarymeans forprecisely andmore etfectivelydetermining and limiting the overall operating range of the tension ,rod of the knitting machine.

,It is understood 'thatlevers 14 and-:associatedspring means .and high 'frequencyreactive resilient means associated therewith maybeprovided'at the opposite ends ofthe yarn supply beam 202:. Itis understood, that for safety purposes, a micro-switch, not shown, in circuit with the motor drive of the machine, may be suitably. located for actuation in response to excessive movement of thetension'rod 12 in either direction to points beyond the normal operating range thereof, to automatically stop the machine.

Additionally, yarn tensioning means 10a comprises-a resilient member 24 in the form of a rubber cushion slidably mounted on a rod 25, which rod is attached at one end thereof to the machine frame. The cushion 24- abnts lever 14; the rod 25 passing through an opening 26 in said lever. The rod '25 is threaded at the other end thereof anda nut27 is screwed on the threaded portion of 'the rod, with the cushion 24 fixed to said nut to allow the cushion to be adjustably positioned relative to lever 14.

It will be apparent that the downward movementof tension rod 12 will be limited by the compressabilityof cushion 24. Thus, during the knitting cycle, yarns from sheet Y will llowin response to the high frequency reiactive tensioning action caused by the abutment of lever 14 against cushion 24. The axial length of cushion l2 4f is sufiicient to providevthe necessary yield of tension rod 12 to follow the required temporary yield in the yarns in response to the momentary needs of the knitting motions over and beyond the current supply of yarn of the oscillatory bar 511. Furthermore, the yarn beam supply maybe positively'driven, by .anysuitable means to impart. a desired linear speed to the yarns Y as they move overthe tension'rod 12 to the knitting elements 21.

As various changes might be made in the embodiments of the inventionherein described without departing from the spirit thereof, it is understood that all matter herein shown or described shall be deemed illustrative and not by way of .limitation except asset forth in the appended claims.

Having thus disclosed myinvention, I claim as new and desire to protect by Letters Patent:

1. In. a' knitting machine, tensioning meansfor the yarns comprising an oscillatory bar, a tension rod extending parallel to said bar, means forrigidly and immovably fixing said:rod torsaidbarfor conjoint movement, lever means projectinglaterally from said bar, spring meansoperatively related to :said levermjeans for controlling the oscillatory'rnovement of said bar in response to variations in tension of yarns moving over said rod, and auxiliary resilient cushion means operatively, engageable withsaid lever-means for limiting the range ofrmovement of said oscillatory bar.

2. A knitting machine as in claim'l and further includingmeans for mounting said auxiliary resilient means in adjusted positions relative to said lever means.

.3. Akn'ittin'g machine as in claim 2 and further including means for adjusting the position of said auxiliary resilient means relative to thelongitudinal' extent 1 5 of saidlever means 'to "vary. the, leverage ratio' between said lever means and the means thing the tension rod to said bar.

4. In a knitting machine, tensioning means for the yarns knitted by said machine comprising an oscillatory bar, a tension rod, means connecting said bar and rod in parallel relation, lever means extending laterally from said bar, spring means for controlling the oscillatory movement of said bar, andhigh frequency responsive resilient rubber cushion means located opposite said lever means for abutment thereby to limit the oscillatory movement of said bar.

5. Yarn tensioning means for a knitting machine comprising a bar mounted on the frame of the machine for oscillatory movement, a tension rod extending parallel to said bar, means for fixedly attaching said rod to said bar, lever means extending laterally from said bar, bracket means on the frame of the machine including an arm fixedly located opposite said lever means, high frequency reactive resilient means mounted on said bracket arm for abutment by said lever means upon oscillatory 20 movement of said bar, and resilient means connecting said lever means and the frame of said machine for controlling the oscillatory movement of said bar.

6. Yam tensioning means as in claim 5 and further including means for locating said first mentioned resilient means in adjusted positions along said bracket arm.

,7; Yarn tensioning means for a knitting machine comprising a bar mounted on the frame of the machine for oscillatory movement, a tension rod extending parallel tosaid bar, means for fixedly attaching said rod to said bar, lever means extending laterally from said bar, spring means operatively related to said lever means for controlling the oscillatory movement of said bar, means for locating high frequency responsive resilient means in the path of movement of said lever means for abutment thereby, and means for adjusting the position of said resilient means to vary the distance thereof relative to the pivotal point of said lever means.

References Cited in the file of this patent UNITED STATES PATENTS 2,383,562 Plunkett et a1. Apr. 28, 1945 2,667,773 Hepp Feb. 2, 1954 2,674,110 Roughsedge et a1. Apr. 6. 1954 

